Antifungal susceptibility, serotyping, and genotyping of clinical Cryptococcus neoformans isolates collected during 18 years in a single institution in Madrid, Spain.

We studied the serotypes, mating-types, AFLP genotypes, and antifungal susceptibility of 58 Cryptococcus neoformans strains causing 56 episodes of cryptococcosis in 55 patients over an 18-year period in a single institution. The underlying conditions of the patients were classified as HIV infection (n = 48) or non-HIV-related immunodeficiency (n = 7). Serotype A (n = 34; 58.9%) predominated, but serotype AD was involved in 23.2% of episodes. Most of the episodes were caused by mating-type α (n = 41; 73.2%) or α/a strains (n = 12; 21.5%). The most common genotype was AFLP1 (n = 26; 44.8%), followed by AFLP3 (n = 21; 36.2%), and AFLP2 (n = 11; 19.0%). In two different patients, we showed the coexistence of different serotypes and/or genotypes in the same episode (AFLP1 and 3). The new triazoles voriconazole, posaconazole and isavuconazole showed high and similar antifungal activity (MICs ≤ 0.125 μg/ml). Fluconazole also had good antifungal activity, but two strains from patients with HIV-infections had an MIC of 16 μg/ml (3.4%). However, these two isolates remained very susceptible to the new triazoles (MICs ≤ 0.062 μg/ml). The remaining strains always showed MICs ≤ 8 μg/ml.